Cricklewood Glass - Quality Products & Services Since 1986

Now At Larger Premises: Unit 6d, Atlas Business Centre, Oxgate Lane, London, NW2 7HJ

Glass - Glazing - Secondary Glazing - Soundproof Windows - Splashbacks & Worktops -  Double Glazing & Units - Mirrors - Table Tops - In fact, Everything Glass!

Secondary Glazing - Secondary Double Glazing, Secondary Windows & Internal Double Glazing



London Secondary Glazing - Quality Secondary Windows, for Noise and Sound Proofing, Heat and Energy Insulation - Expert Installations, a Friendly, Ethical Service and Great Value for Money!

This page provides an overview of our Secondary Double Glazing products and services - for Heat Insulation, Noise, Condensation and Security - for Casement and Sash Windows as well as for Doors.

Based in North West London, we are within 15 minutes’ access of the M1, the A1, the A10, the North Circular, the South Circular, the M25 and the M40 - we carry out installations throughout London, Hertfordshire, Bedfordshire, Essex, Kent, East and West Sussex, Surrey, Hampshire, Berkshire, Oxfordshire and Buckinghamshire.

Download our Secondary Glazing Brochure pdf

About Us

Counter Balanced Vertical Slider over a Traditional Sash Window for Noise and Heat, London Secondary Glazing

We are a well-established Glass Merchant and Glazing Company - specializing in Quality Aluminium Secondary Glazing since 1986. We serve all London Post Codes, the City, Greater London and the Home Counties.

Quality and Service are our keywords and we provide the very best quality products, installations, service and after-sales service.

We are happy to provide advice and information by telephone or email and we are always pleased to put you in touch with "local-to-you" customers, so that you can take up references and see the quality of our work.

Our experience is that people want friendly, quick, honest advice and a prompt, reliable service.

We aim to make dealing with us a stress-free experience from start to finish.

From initial enquiry, through to supplied products or a completed installation.

Secondary (Double) Glazing - Secondary Windows - Internal Double Glazing

Secondary Windows fitted to an Office Refurbishment for Heat Insulation and Noise Reduction London Secondary Glazing

Secondary Glazing, Secondary Double Glazing, Secondary Windows and Internal Double Glazing are all just different names for the same product - a second layer of glazing fitted inside the existing windows and doors.

Whilst other Suppliers have come & gone, we have continuously maintained a strong presence with this product for over 30 years.

Secondary Glazing is eminently suited to London and the Home Counties, with their unique blend of Historic, Period and Modern properties, both Residential and Commercial.

Secondary Windows - All the Benefits

Brown Finished Secondary Windows fitted to Original Metal Crittall Windows, Home Counties, London Secondary Glazing

A quick summary of all the Benefits of Secondary Glazing Windows and Doors:

Secondary Window Systems - Design & Installation Criteria

Legacy Range Secondary Double Glazing – for Discreet, Unobtrusive Noise Reduction and Energy Conservation, London Secondary Glazing

In response to Customer Demand, the Design Criteria for our Secondary Double Glazing Range is for products that are Robust & Functional, as well as Complementary & Unobtrusive once installed.

Our products are both strong and very discreet, made and fitted to match in with modern surrounds and décor as easily as they blend into traditional timber Sash Windows and Elizabethan Metal Casements with Leaded Lights.

In fact, they have been designed so that once fitted, they are not seen!

Every property is different, so we take great care to specify the correct Secondary Glazing units for the individual windows and doors, ensuring that:

  • the original vertical mullions & horizontal transoms line up with the secondary units
  • maximum light and clear views are maintained
  • there is easy access for cleaning all glass surfaces of both the secondary and the original windows

Our Concealed Fixing System and wide range of Moulded Finish Sections are used to achieve a perfect finish that is in keeping with both the original windows and doors and your décor.

Our Installations Gallery has pictures of all types of installed Secondary Glazing

Unique Survey & Installation System for Internal Double Glazing

Fitting Hand Made Sub Frame to Curved Head Double Casement Window for Internal Double Glazing London secondary Glazing

With over 30 years of experience, we have developed the very best system for Measuring and Installing Internal Double Glazing to achieve a perfect fit, both technically and visually.

When we come to do the survey, before we do anything else, we fit the timber sub-frames, including scribing and fitting to any shaped frames and out of square openings.

At the same time, we check and make provision for any telephone or burglar alarm wiring and any pelmets, blinds or curtain rails that may interfere with the installation or the correct operation of the secondary glazing after installation.

Then and only then, do we measure for the actual secondary glazing.

To the best of our knowledge, we are the only Company using this method.

You can see full details and pictures on the Unique Survey & Installation System page.

Secondary Glazing Energy Saving - Thermal Insulation - Reduce Heating Bills

Heat Loss via Draughty, Single Glazed Windows, is Estimated at up to 30%

Upgrading the Heat Insulation of Single Glazing is essential these days and it can be very expensive, so it pays to carefully consider the options, before deciding.

We also replace all types of windows and doors using traditional timber construction as well as modern uPVC and Aluminium systems - so we have no particular axe to grind and can offer unbiased advice.

  • Every situation is different - but heat loss via draughty, single glazed windows, is estimated at up to 30% of a homes’ total poor insulation heat loss.
  • If you think of your annual heating bills, then you can easily calculate how quickly a 30% reduction would pay back your installation costs.

For more information and how to evaluate the best solution for you, please see our Heat & Energy Insulation page also our Savings Calculator

Secondary Glazing Noise Reduction & Sound Proofing

The Acoustic Range of Secondary Windows and Doors for Noise Reduction and Soundproofing London Secondary Glazing

Most noise enters our homes via the windows & doors.

The windows are designed to let the light in and create an airy, pleasant atmosphere - unfortunately, they also allow the noise in from outside.

Our Special Acoustic Range of Secondary Windows and Doors, developed over more than 25 years, provides the most effective Noise Reduction available today.

We are experts in specifying for the very best Soundproofing in any given situation.

Where the noise is very severe, we specify specialist Stadip Silence ® Acoustic Laminated Glass, achieving up to:

50 dB (Decibels) Noise Reduction - which represents - a 90% Reduction in the Noise!

London Secondary Glazing Reviews - Noise Reduction

We Install Acoustic Secondary Glazing Specified Against Aircraft Traffic Train and Street Noise Secondary Glazing London Tested and Proven for Soundproofing and Noise Reduction Secondary Glazing London

The proof of the pudding is in the eating - these are a few Typical Comments from our customers after we have installed our Acoustic Range of Secondary Glazing:

...noise reduction has been considerable longer disturbed by traffic noise

the result is a considerable reduction in noise levels from passing trains

...and the noise is so quiet. Amazing. We will definitely recommend your company.

...looks particularly good because I can't see it. The acoustic barrier it provides is excellent.

...that makes a huge difference to the traffic noise & you hardly notice they're there!

...have reduced the noise and kept in the heat, as promised.

The reduction in noise is dramatic.

A great service & fantastic product - the sound reduction is excellent.

Definitely recommended. No more noise.

Very impressive. A significant improvement to the level of noise

Excellent. Beautifully fitted and very neat. An instant reduction in noise.

...very pleased with the noise reduction

It has made an appreciable difference, and I am sure the children will sleep well.

The full text and details of the above, plus more evaluations, can be found in Customer Reviews and for more detailed information, please see the Soundproofing & Noise Reduction Case Studies

Secondary Double Glazing for Sash Windows

The Legacy Range of Secondary Sash Windows for Heat and Noise Insulation Secondary Glazing London

Sash Windows have been installed in London and the surrounding areas for over 400 years, they are still being installed today and conservative estimates suggest that there are between 15 and 20 million of them in and around London!

Traditional Sash Windows present particular challenges for sympathetically upgrading both Heat and Noise Insulation as well improving Security.

Our specially designed Legacy Range ® of Secondary Sash Windows, provide solutions to all of the challenges, achieving excellent Thermal Insulation, Noise Reduction and upgraded Security with discreet but highly functional secondary double glazing units.

We ensure an attractive, discreet installation that allows - safe and easy access to both the Secondary and the Original Sash Windows - for opening, closing and cleaning - whilst also providing modern levels of Heat Insulation and truly excellent Soundproofing.

All about Secondary Double Glazing & Sash Windows is here

Listed Buildings, Conservation Areas & Secondary Glazing

Secondary Glazing the Ideal Solution for Conservation Areas Listed Buildings Leaseholds Joint Freeholds Secondary Glazing London

An increasing number of properties are now in Conservation Areas or are Listed Buildings - additionally many are Leasehold or Joint Freehold - these place restrictions on how Windows & Doors can be replaced or altered.

To improve Thermal Efficiency or Soundproofing, Secondary Glazing is often the only solution.

Fortunately, it is usually the Best Solution as well!

Over the years, we have become experts in dealing with these issues - for in depth information please see the Listed Buildings & Conservation Areas page.

Our Heat and Energy Case Study features Listed Sash Windows and the Secondary Glazing Installations Gallery has lots of examples of Listed, Historic and Heritage Windows with all the different types of our Secondary Glazing installed.

Secondary Windows for Condensation Control

Properly Specified Secondary Glazing Resolves Condensation on both Double and Single Glazed Windows Secondary Glazing London

Condensation on Windows and Walls is another area requiring in depth experience to provide properly specified Secondary Window solutions that actually work.

The results of Condensation are easy to see - moisture on the glass, mould growth and rot in timber windows, rust and flaking paintwork on metal windows.

In these situations, it is essential to identify the root causes and then specify the correct solutions for each individual case.

We are fully experienced in this area and how we go about resolving Condensation Problems is covered in our Condensation Control section.

Secondary Double Glazing for Security

Secondary Double Glazing Increases Security and for Vulnerable Windows Fit Child Safety Locks Secondary Glazing London

Fitting Secondary Glazing for Heat, Noise or Condensation also greatly enhances the Security of Windows and Doors by adding a second Visible Physical Barrier against Forced Entry.

For Vulnerable Areas and where Security is the Primary Issue, specifying Laminated or Toughened Glass, plus Key Locking Security Locks to the Secondary Glazing, boosts Security even further.

For Maximum Security in exceptional circumstances we can install High Security Secondary Windows featuring:

  • Colour Matched Steel Frames
  • Frame Fixings bolted through into the fabric of the building
  • A range of different types of High Security Glass:
    • Impact Resistant
    • Blast Resistant
    • Bullet Proof

More information about Secondary Glazing for Security

Secondary Glazing, Residential & Commercial Installations, Trade & DIY Supplies

Secondary Glazing Residential and Commercial Installations Trade and DIY Supply Secondary Glazing London and Home Counties
As well as Secondary Double Glazing Residential Installations across London and the Home Counties, we also:

We are fully experienced in working with Home Owners, Commercial Specifiers, Architects, Interior Designers, Landlords, Local Authorities and Conservation Officers.

All materials and products are rigorously Quality Controlled during the production process and wrapped for protection during transit.

As part of our Hassle Free approach to doing business and providing the Highest Quality Products and a Friendly Customer Service:

Secondary Glazing - Product Range

Coloured Frames Curves Arches Semi Circular Circular Fly Screens Special Shapes and Glass Types Available Secondary Glazing London
Lift Out Units for Fixed Casements allow Easy Removal for Cleaning when Required, Secondary Glazing London
Horizontally Sliding Units from Two up to Six Panels to suit Casement Windows Secondary Glazing London
Vertically Sliding Units for Sash Windows and Hinged Units for Doors and Windows Secondary Glazing London

We have a comprehensive range of units to suit every type of window and door:

Standard Secondary Glazing Types

  • Horizontally (side to side) Sliding Units
  • Vertically (up and down) Sliding Units
  • Hinged Units
  • Lift-Out Units
  • Fixed Units


  • Casement Windows
  • Sash Windows
  • Casement Windows & Doors
  • Small Casement & Sash Windows
  • Fixed Windows & Part Glazed Doors

Our standard frame finish is White, we also stock Brown and Silver finishes and can paint finish to any RAL colour to match or complement your internal colour scheme & decoration.

In addition to the above, we also manufacture Specialist Secondary Glazing of all types, including:

Special & Bespoke Secondary Glazing

  • Curved
  • Semi-Circular & Circular
  • Arched Heads
  • Triangular
  • Fly Screens
  • With Trickle Vents
  • Specialist Glasses


For further information about our Secondary Windows and Doors, please refer to the Menu or follow the links below:

Other Products & Services

We also Supply and Install Glass Balustrades Staircases and Decking Showers Splashbacks Mirrors Secondary Glazing London

As well as Secondary Glazing, we also supply and install:

  • Shower Screens, Enclosures & Doors
  • Kitchen & Bathroom Splashbacks
  • All types of Double Glazing
  • Glass Roofs
  • Patent Glazing
  • Glass Walls
  • Table Tops
  • Cut to Size Mirrors
  • Mirror Installations
  • All types of Glass
  • Glass Privacy Screens
  • Skylights
  • Glass Replacement
  • Glazing Repairs
  • Made to Measure Double Glazed Units
  • Hole Cut-Outs for Fans, Dryers & Air Conditioning
  • Glass Staircases & Balustrades
  • Glass Decking
  • Mirror Walls

Please go to the Menu or our Home Page for further information

Download our Secondary Glazing Brochure pdf

Thank you for visiting - please Contact Us if we can be of any further help.